Backpack



FIG. 1 is a top, front, right perspective view of a backpack showing ournew design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a top, rear, perspective view of a backpack in an alternativeconfiguration thereof.

The broken lines represent portions of the backpack or stitching andform no part of the claimed design.

CLAIM The ornamental design for a backpack, as shown and described.